Return to the Planet of the Apes Episode 9 Trail to the Unknown Episode Title:Trail to the Unknown.Episode Description:Bill, Jeff and Judy begin building rafts to help the human tribe reach New Valley on the river and escape Urko's patrols. In Ape City, Dr. Zaius visits Cornelius and Zira in their lab to thank them for stealing Urko's plane. By doing so, he feels that they have saved simian society from Urko's dictatorship. They again assure him that they had nothing to do with the stolen plane, but Zaius insists that their secret is safe with him. He leaves them with the news that Urko has been given permission to attack the human caves to find Blue Eyes...